PLL Power Converter Bandwidth Control Under Voltage Variations
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Solution Overview
Problem
Existing power converters, such as hysteretic buck converters, face challenges in minimizing locking time and achieving desired bandwidth due to variations in input and output voltages, which affect the gain of the voltage-controlled oscillator (VCO) and stability.
Innovation Solution
A phase-locked loop (PLL)-based power converter with a compensation circuit that generates a charge pump current, making the PLL transfer function independent of input and output voltage variations, thereby minimizing locking time and achieving increased bandwidth with minimal impact on stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the PLL bandwidth is increased to reduce locking time, then the locking time is reduced, but the stability of the power converter deteriorates due to voltage variations affecting VCO gain
Solution Approach 1:
The patent changes the parameters of the charge pump current to compensate for VCO gain variations. By adjusting the charge pump current based on detected voltage variations, the system maintains stable PLL performance across different operating conditions, resolving the contradiction between fast locking and stability.
Solution Approach 2:
The patent implements a feedback mechanism that detects voltage variations and uses them to adjust the charge pump current. This feedback loop compensates for VCO gain changes, allowing the PLL to maintain stability while achieving fast locking times even under varying input and output voltage conditions.
2Speed
If the VCO gain is increased to improve PLL bandwidth, then the PLL bandwidth is increased, but the sensitivity to voltage variations increases, making stability control more difficult
Solution Approach 1:
The patent dynamically changes the charge pump current parameter to offset the effects of high VCO gain under voltage variations. This allows the system to maintain high PLL bandwidth while compensating for increased sensitivity to voltage changes, thereby preserving stability control.
Solution Approach 2:
The feedback mechanism detects voltage variations and adjusts the charge pump current accordingly, counteracting the increased sensitivity caused by high VCO gain. This enables the system to achieve wide PLL bandwidth while maintaining reliable stability control despite voltage fluctuations.
3Adaptability or versatility
If the charge pump current is made dependent on voltage variations, then the PLL transfer function becomes adaptive, but the device complexity increases
Solution Approach 1:
The patent implements parameter changes in the charge pump current based on voltage detection, making the PLL transfer function adaptive to operating conditions. This approach achieves adaptability through relatively simple parameter adjustments rather than complex structural modifications.
Solution Approach 2:
The feedback mechanism provides adaptability by automatically adjusting the charge pump current in response to voltage variations. This feedback-based approach achieves transfer function adaptability with minimal additional circuit complexity, as it uses existing voltage detection capabilities to drive the adjustment.
Data Source
AI summary
A phase-locked loop (PLL)-based power converter is disclosed. A power converter includes a switch circuit having a switch node coupled to a regulated power supply node via an inductor and configured to source a supply current to the regulated power supply node using one or more control signals. A control circuit performs a phase-frequency comparison of a reference clock signal and a switching frequency of the switch circuit and generate a control voltage using results of the phase-frequency comparison. The control circuit further generates a control current using the control voltage, a voltage of the regulated power supply node, and a duty cycle of the switch circuit, and a demand current using the voltage level of the regulated power supply node and a reference voltage. Using the demand current, the control current, and a sensed version of the supply current, the control circuit generates the one or more control signals.